Soil adhering to clothes is generally classified into organic soil and inorganic soil. Muddy soil is a typical inorganic soil. Muddy soil very commonly adheres to, for example, socks, and has been known as one of the most difficult soils to remove. Surfactants and builders, which are active components of a detergent for clothes, have relatively weak effects against inorganic soil. Therefore, a variety of technologies have been developed to enhance wash-off effect against inorganic soil. However, most of them are applied technologies making use of conventional detergent bases and have respective drawbacks. For example, carboxylic acid-based polymers such as carboxymethyl cellulose or polyacrylate, having the effect of dispersing mud therein, are difficult to incorporate in a sufficient amount due to cost and bio-degradability. Use of reducing agents have also been proposed; however, it still has a problem upon incorporation because reducing agents may sometimes cause decoloration of dyed clothes.
Besides the application of the aforementioned conventional substances, there have been made attempts to use an enzyme to enhance washing effect against inorganic soil. Since an enzyme acts exclusively on a specific substrate, it exerts effects at a small amount of incorporation. Thus, an enzyme is an excellent detergent base and is expected to play more significant roles in detergent compositions. Japanese Patent Application Laid-Open (kokai) No. 59-49279 discloses that incorporation of cellulase into a detergent increases washing power against mud. Also, PCT Kohyo Publication No. 3-504080 discloses a certain cellulase which reduces harshness of cotton-containing fabrics and has effect of removing soil. Furthermore, WO95/25790 and Japanese Patent Publication (kokoku) No. 6-39596 disclose a detergent containing pectinase. Particularly, Japanese Patent Publication (kokoku) No. 6-39596 discloses that pectinase is effective against muddy soil. However, pectinase disclosed in these patent publications exhibits insufficient washing effect even when washing is conducted after presoaking at 40.degree. C. for one hour.
In view of the foregoing, an object of the present invention is to provide a detergent composition having excellent detergency against muddy soil.